Table 1 The criteria list of quality score for included studies
Criterion | Score |
|---|---|
Representativeness of cases | |
 Selected from population or cancer registry | 3 |
 Selected from hospital | 2 |
 Selected from pathology archives, but without description | 1 |
 Not described | 0 |
Source of controls | |
 Population based | 3 |
 Blood donors or volunteers | 2 |
 Hospital based (cancer-free patients) | 1 |
 Not described | 0 |
Case-control match | |
 Matched by age and gender | 3 |
 Not matched by age and gender | 0 |
Specimens used for determining genotypes | |
 White blood cells or normal tissues | 3 |
 Tumor tissues or exfoliated cells of tissue | 0 |
Hardy–Weinberg equilibrium (HWE) | |
 Hardy–Weinberg equilibrium in control subjects | 3 |
 Hardy–Weinberg disequilibrium in control subjects | 0 |
Total sample size | |
 > 1000 | 3 |
 > 500 and < 1000 | 2 |
 > 200 and < 500 | 1 |
 < 200 | 0 |